<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Handles Base 64 Encoding in Swift Mailer.
 *
 * @package    Swift
 * @subpackage Encoder
 * @author     Chris Corbyn
 */
class Swift_Encoder_Base64Encoder implements Swift_Encoder
{
	/**
	 * Takes an unencoded string and produces a Base64 encoded string from it.
	 *
	 * Base64 encoded strings have a maximum line length of 76 characters.
	 * If the first line needs to be shorter, indicate the difference with
	 * $firstLineOffset.
	 *
	 * @param string $string to encode
	 * @param integer $firstLineOffset
	 * @param integer $maxLineLength optional, 0 indicates the default of 76 bytes
	 *
	 * @return string
	 */
	public function encodeString($string, $firstLineOffset = 0, $maxLineLength = 0)
	{
		if (0 >= $maxLineLength || 76 < $maxLineLength) {
			$maxLineLength = 76;
		}

		$encodedString = base64_encode($string);
		$firstLine = '';

		if (0 != $firstLineOffset) {
			$firstLine = substr(
					$encodedString, 0, $maxLineLength - $firstLineOffset
				) . "\r\n";
			$encodedString = substr(
				$encodedString, $maxLineLength - $firstLineOffset
			);
		}

		return $firstLine . trim(chunk_split($encodedString, $maxLineLength, "\r\n"));
	}

	/**
	 * Does nothing.
	 */
	public function charsetChanged($charset)
	{
	}
}
